This invention relates to circuit interrupters, and more specifically relates to a high-speed vacuum interrupter which can attain switching times of less than one millisecond. There are many applications which require extremely high speed interruption of a circuit. As one example of such applications, a very high speed interrupter is useful in fault current-limiting interrupters in which high speed contacts are opened to commutate main circuit current into current-limiting devices. In general, the vacuum interrupter is opened synchronously a short time before the circuit produces a current zero. The short arcing time reduces contact erosion and allows the interruption of high power levels. The arcing time preferably is somewhat less than one millisecond. Many other applications for extremely high speed interrupters exist.
Vacuum interrupters are well known and use the high dielectric strength of a vacuum to interrupt circuits with a relatively small interrupting gap. In the past, the high speed recovery characteristics of the vacuum have produced current chopping and this has been an undesirable characteristic of the vacuum interrupter.